The present invention relates to a water collection and drain pipe which is generally called an underdrain pipe and buried in the ground in use, and particularly relates to a pipe buried in the ground such as prepared grounds for housing, golf links, agricultural land, retaining walls, or banks, and used for collecting rainwater or a spring in the ground, guiding and draining the water to a predetermined drainage channel.
Heretofore, such an underdrain pipe is well known and used broadly. Such a conventional underdrain pipe is generally a cylindrical pipe made of synthetic resin and formed into a spirally corrugated shape. (For example, see Japanese Utility Model Unexamined Publication No. Sho 61-93528)
In the case of such a pipe formed cylindrically, the stability thereof is poor when the pipe is buried and subjected to piping in the ground so that the pipe is apt to be twisted in the circumferential direction of the pipe. Therefore, in the case where small holes for collecting water are formed in the pipe except a predetermined angle region in the circumferential direction of the pipe in order to surely drain water which is once collected in the pipe, even if it is designed in advance so as to dispose the pipe in a manner so that the portion having no small holes comes downside, it is difficult to surely make this portion having no small holes come downside because of such a twisting phenomenon of the pipe. Therefore, a conventional underdrain pipe has a structure that small holes for collecting water are formed over the whole region of the pipe in the circumferential direction of the pipe.